<p>A foreign key operation would insert or update a row that duplicates a key already present in the child table.</p>
<p>MySQL Error 1762 ER_FOREIGN_DUPLICATE_KEY_WITHOUT_CHILD_INFO happens when an INSERT, UPDATE, or DELETE violates a foreign key by generating a duplicate child-row key. Check unique indexes on the child table, adjust the conflicting value, or remove the duplicate row to clear the error.</p>
Foreign key constraint for table '%s', record '%s' would
Error 1762 appears when a foreign key constraint attempts to create a child record whose primary or unique key already exists. MySQL blocks the change to keep relational integrity.
The message includes the parent table and conflicting record so you can identify exactly which value is duplicated.
The error fires during INSERT, UPDATE, or cascading DELETE operations that reference a child table containing a unique key or primary key duplicate.
It is frequently seen after bulk loads, incorrect data migrations, or manual updates executed without checking existing child keys.
Leaving the constraint unresolved prevents new data from committing and can halt application workflows. Fixing it preserves referential integrity and ensures accurate query results.
Common triggers include missing unique indexes on referenced columns, manual inserts that bypass application logic, and mis-ordered data loads where child rows arrive before parents.
Identify the duplicate key, remove or update the conflicting child row, then retry the statement. Alternatively, modify the foreign key or unique index to accept the intended duplicates if business logic allows it.
During bulk import, load parent tables first or disable foreign keys temporarily, then re-enable and clean duplicates with SQL scripts.
In OLTP applications, add defensive checks in code to confirm a child row does not already exist before inserting.
Keep parent tables populated before inserting to child tables, maintain proper unique indexes, and validate incoming data in staging tables.
Errors 1452 (cannot add or update child row) and 1216 (cannot add or update parent row) are similar foreign key violations. They differ in the kind of integrity issue but can be fixed with the same investigative approach.
An identical primary or unique key row is present, so the new operation clashes.
During bulk loads the child table receives data before the parent, creating duplicates once parents load.
ON UPDATE or ON DELETE CASCADE actions propagate duplicate values unintentionally.
Columns defined in the foreign key lack matching unique constraints, leading to unexpected duplicates.
Occurs when the referenced parent row does not exist.
Raised when trying to delete a parent that still has child references.
Another foreign key violation focused on parent table constraints.
It lets the statement succeed but leaves data inconsistent. Use only for one-off migrations and clean data afterward.
You can drop the unique index, but this may break business logic. Evaluate carefully before loosening constraints.
Run GROUP BY queries on the child table’s key columns and filter HAVING COUNT(* ) > 1.
Galaxy surfaces MySQL error codes in the editor, allowing quick navigation to documentation and collaborative troubleshooting.
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